The opening reunion between Clarke and her mother, after Clarke de-chipped Abby using Raven's EMP device, was intensely emotional. Paige Turco perfectly played the horror and devastation of Abby remembering that she'd tortured her daughter, as Clarke tried to reassure Abby that she knew it wasn't Abby doing those horrible things.

Even in the midst of actual world-ending chaos, Clarke took a moment to comfort her distraught mother. These two have one of the most complex, fully-realized mother-daughter relationships on TV, and I love it.

Luckily for everyone, Clarke had a crazy, dangerous last-ditch idea to save the day: she'd transfuse Ontari's Nightblood into her own body, Mount Weather-style, so that Clarke herself would (hopefully) be able to take the flame of the Commander without it liquefying her brain as it had Emerson's.

I took a vague guess in my review of The 100 Season 3 Episode 15 that Clarke's final gambit would involve Ontari's blood – there was more than one lingering shot on the blood leaking from Ontari's head where Jaha had hit her. Seemed like foreshadowing.

Also foreshadowing, in retrospect: way back on The 100 Season 3 Episode 4, there was that moment when Queen Nia (after Clarke attempted to assassinate her) cut Ontari's hand and allowed the black blood to drip onto Clarke's face.

Given that Clarke would later take that same blood into her own body – that seemingly random moment seems so much more significant.

No one was comfortable going through with Clarke's plan, but they did it anyway, because they all trust her. Given that ALIE's chipped soldiers were literally climbing up the tower to get to them, they also didn't have much of a choice.

The tension during the moment when Ontari's blood finally entered Clarke's bloodstream was unreal. The musical score just amped up that tension, when even Clarke was visibly nervous to see what effect the blood would have on her. But the blood didn't kill her, and the flame didn't kill her.

With Becca's knowledge from the flame, Clarke realized that she needed to enter the City of Light and that she'd know what to find once she was in there.

The whole thing with Clarke's innate knowledge immediately garnered from the flame was just a little bit silly, but necessary for plot purposes. Essentially, that flame is pure plot device.

Once Clarke entered the City of Light, she appeared to be wearing the same exact outfit she'd worn from the series premiere, as she dropped to Earth with the other delinquents. That was a really neat detail, given that the inhabitants of the City of Light were allowed to determine their appearance – on some base level, Clarke wanted to be that far more innocent version of herself that she was once, at the beginning. Can't say I blame her. She's seen some things.

Once inside the City of Light, Becca's voice called out to Clarke and generated infinity symbols (like those on the ALIE chips) that served as a sort of trail of breadcrumbs to the killswitch. That was a neat effect, too.

While Clarke followed the symbol on street signs and in a woman's hairdo, back in Polis, the chipped soldiers scaled the tower (led by Kane) while Clarke's friend acted as guards, holding off the army.

This could have been an incredibly dull use of everyone's time – everyone playing "keepaway the Clarke" with the chipped army while Clarke had all the action inside the City of Light, essentially – but for a few significant character development moments that occurred in the "real world."

For one, the tension between Octavia and Pike could be cut with a knife – or a machete. In fact, the biggest source of tension for me, watching this episode, wasn't whether Clarke would save everyone from ALIE (I felt sure she would; she's Clarke) – it was whether (and eventually, when) Octavia would kill Pike.

After trying (and failing) to disarm Pike and let the chipped soldiers dispatch of him for her, Bellamy tried to warn his sister off going down the beaten path of vengeance. Once she left the room briefly, however, Pike had a chance to reveal his continued stance on Grounders.

Pike: It wasn't the wrong side. If the Grounder army was still there when Lexa died, they would have attacked. And you know it.Bellamy: I wanted to see things like you. I needed that. To believe that they were bad, and we were good. I don't know what I believe anymore. I just know I have to live with what I've done.

This, right here, was a perfect distillation of why Bellamy's redemption arc can still happen and why Pike's could not.

As Kane told Bellamy earlier in the season about turning in Pike to the Grounders, it mattered whether Bellamy's change of heart came down to realizing it was the right thing to do or his love for Octavia.

Similarly, Bellamy's forgiveness was dependent on whether he realized what he'd done was wrong and that Pike's mentality towards Grounders was wrong.

Bellamy isn't quite at the level of loving Grounders, but he's unwilling to accept Pike's mindset and realized his actions had been wrong. He'd live with those deaths, that blood on his hands. Pike didn't (or wouldn't) get any of that. For that reason, Pike would die.

Murphy and Abby also worked together, while the others held down the fort, to keep Clarke alive, with Ontari's Nightblood pumping through her veins. To do that, they eventually had to resort to the grisly method of literally cracking open still-technically-alive Ontari's chest cavity and manually pumping her heart.

Abby was very much like Clarke in that moment – or, more accurately, we can see where Clarke got her strength and resilience from. Clarke, like her mother, is the type of person who wouldn't let horrific medical procedures stop her from saving everyone throughout these three seasons.

I'm not a squeamish person, but that was tough to watch. Also, Ontari wasn't exactly a great person, but to see her body essentially desecrated like that left me feeling a little weird. I mean, desecrating her body did save everyone from ALIE, but it was also horrifying, on a deep physical and emotional level.

While Abby and Murphy kept Clarke alive and Bellamy, Pike, Octavia and the others kept the chipped soldiers at bay, back in Arkadia, Monty, Raven, and Harper were busy, too.

After disarming and tying up chipped Jasper, they ran the program and realized that Clarke was in the City of Light and that the Clarke-virus inside the City of Light was allowing ALIE to upgrade to ALIE 2.0 – which would enable ALIE to permanently delete the kill switch.

I loved that Raven wound up being an integral part of ALIE's defeat in the end, using her coding skills to help Clarke find the entrance to ALIE's killswitch.

Of course, Raven wasn't the only one to come in with the big assist for Clarke.

Lexa arrived, in full Commander gear, to save Clarke when the minds within the City of Light turned on Clarke, attacking her. Her entrance was epic. Just utterly epic. She looked like a warrior goddess; so alive, so happy, so in charge.

Even more powerful than her entrance was the emotional reunion she and Clarke had a chance to share. The hug they shared was so intense and emotionally wrought. The kiss, when Clarke revived after the flame nearly liquefied her brain, was even better. Eliza Taylor and Alycia Debnam-Carey were absolutely phenomenal in these scenes.

Also, this line (and Alycia's delivery) – just amazing:

Clarke: I never thought I'd see you again.Lexa: I told you my spirit would choose wisely.

It wasn't a surprise to many viewers that Lexa made a reappearance in the finale (photos from filming those scenes had been leaked much earlier this year).

Despite the lack of a shock, the reappearance was so very necessary. It tied up Lexa's arc (and the Lexa/Clarke romance) in a far more satisfying way than her initial departure.

I mean, I'm still not thrilled that she's gone, but this was at the very least much, much better than a cheap stray-bullet death.

The visual goofiness of full-Grounder-gear Lexa and Clarke following a little girl with a pink bike and a chip symbol on her jacket was overridden by how thrilled I was to see these two women working together to save the day.

When Raven made the door to the killswitch/Citadel appear and Clarke had to say goodbye to Lexa (yet again), she had a chance to tell her that Lexa that she loved her (finally) and the two shared a beautiful final moment.

Lexa departed like the warrior hero she is – holding off the swarming chipped soldiers so Clarke could enter the citadel and save the day. It was pretty great.

Also worthy of note: Clarke destroyed the City of Light. Lexa was in the flame/ALIE 2.0, not the City of Light. So Lexa lives on, in a sense, in the flame, whether or not she's ever seen again.

Once in the Citadel, the real big twist reared its head, when Becca Pramheda and ALIE both appeared, the angel and the demon, each intending to sway Clarke to either flip or not flip the killswitch.

ALIE wasn't just collecting minds in the City of Light for the hell of it – her drones had picked up radiation from the remaining nuclear power plants that hadn't been destroyed in the apocalypse nearly a century prior. They were melting down and, within half a year, 96% of the earth would be uninhabitable – humanity would die off within six months.

And just like that, a choice that first seemed simple (flip the switch, save everyone, go celebrate at apocalypse Disneyland) became that much more complex. Because that's what this show specializes in. Clarke's fight to defeat ALIE was never going to be as simple as black or white.

ALIE: Let me ease their pain, Clarke. We can save the human race. Together.Clarke: You don't ease pain. You overcome it. And we will.

In the end, despite all she's gone through, Clarke still believes in the perseverance, the strength of humanity – she knows how far humans will go to survive, because she's been there. It's something ALIE, an AI, could never understand, simply because she is not a person.

Clarke chose to buy humanity some time, destroying the City of Light and worrying about saving the Earth from massive irradiation when she was finished with that first problem. Girl seriously can't get a break.

When Clarke flipped the killswitch (which, interestingly, thanks to Clarke's mind controlling everything, took the form of a lever very similar to the one Clarke pulled on Mount Weather), all of the chipped people in Polis immediately stopped killing Clarke's friends and allies.

I was expecting Abby to shoot Jackson, Kane to strangle Bellamy, or that random Grounder to kill Octavia before Clarke switched their pain and memories back on. At least one death then. None of that happened.

What did happen: Octavia very suddenly stabbed Pike, immediately after he'd save her life, shocking everyone – and then she marched right on out of the throne room.

What a way to close out the season! That was easily the craziest moment in the finale. This choice is going to change Octavia catastrophically. I'm so interested to see where her character arc takes her after this cold-blooded killing. And so much for a sacrificial death for Pike's redemption.

I was... kind of sad about it. Michael Beach is a really great actor, despite how awful Pike was.

Finally: it was perfectly fitting that Bellamy would be the one Clarke confides in that they hadn't quite saved the world yet. He was able to read it all over her face, so it made sense for her to tell him. Besides, he'll be at her side when they try to save the world – again – so he was going to find out eventually, anyway.

Questions for Season 4:

Clarke, not being a natural Nightblood, couldn't keep the flame of the Commander and removed it. Who will lead the twelve clans of the Grounders now?

Kane, while still chipped, told Octavia that Indra was still alive – on the cross, having refused the chip – after the explosion. Is that where Octavia went, to get her down, immediately after killing Pike? Headcanon says yes.

Did Roan die? We didn't see him again after he was shot by chipped Kane on The 100 Season 3 Episode 15. Roan and his portrayer, Zach McGowan, are great, so I'd love to find out that he made it out OK somehow.

I'm floored that Jaha made it out of this season alive. FLOORED. What can possibly be next for him, after spending the entirety of The 100 Season 3 as ALIE's right hand man?

Jasper did not look OK after getting out of the City of Light. Despite his heartwarming moment with Monty, I was sure that Jasper would kill himself. I desperately didn't want that (a suicide after a season of a struggle with depression/PTSD would be WAY too dark), but it sure looked like that. Is he on the road to recovery?

Three couples survived the season: Harper/Monty, Miller/Bryan, Kane/Abby. I'm shocked and thrilled. That moment of Abby comforting a distraught Kane was beautiful.

There's gonna be some great world-building next season, yeah? I'm betting the gang will need to travel to these corners of the globe where they'll need to prevent the nuclear meltdowns, and we'll see a lot more of the world of The 100.

What did you think of the season finale? Hit me with your thoughts by commenting below and watch The 100 online to relive this crazy season!